From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by kanga.kvack.org (Postfix) with ESMTP id 00EFD6B2BEB for ; Thu, 22 Nov 2018 10:33:07 -0500 (EST) Received: by mail-ed1-f69.google.com with SMTP id c18so4532312edt.23 for ; Thu, 22 Nov 2018 07:33:06 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id q24-v6si10925143ejb.146.2018.11.22.07.33.05 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 22 Nov 2018 07:33:05 -0800 (PST) Date: Thu, 22 Nov 2018 16:33:02 +0100 From: Petr Mladek Subject: Re: [PATCH v2 09/17] debugobjects: Make object hash locks nestable terminal locks Message-ID: <20181122153302.y5vqovrsaigi6pte@pathway.suse.cz> References: <1542653726-5655-1-git-send-email-longman@redhat.com> <1542653726-5655-10-git-send-email-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1542653726-5655-10-git-send-email-longman@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Waiman Long Cc: Peter Zijlstra , Ingo Molnar , Will Deacon , Thomas Gleixner , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Sergey Senozhatsky , Andrey Ryabinin , Tejun Heo , Andrew Morton On Mon 2018-11-19 13:55:18, Waiman Long wrote: > By making the object hash locks nestable terminal locks, we can avoid > a bunch of unnecessary lockdep validations as well as saving space > in the lockdep tables. Please, explain which terminal lock might be nested. Hmm, it would hide eventual nesting of other terminal locks. It might reduce lockdep reliability. I wonder if the space optimization is worth it. Finally, it might be good to add a short explanation what (nested) terminal locks mean into each commit. It would help people to understand the effect without digging into the lockdep code, ... Best Regards, Petr